Ammeter



g- 6, 1929- R. o. HELGEBY 1,723,035.

AMMETER Filed July 13, 1927 Patented Aug. 6, 1929.

an NIT-JED esrxress were NT JfOFFiiCiE.

' RALPH OIiAF HELGEBY', O1 JFIJINT, 1V1.ICI-IIGEAN," ASSIGNOBJTO A' C SPARK"PLUGZCOM 'PANYTGF FI'zINT, MICHIGAN}, A COMPANY" GF' M'I'CHIGAN.

' 'LAMMETER.

Application filed Julyi 13 This invention relates to an. ammeterr and moreparticularly to an annneter of the :type ordinarily.mounted-on the dashboard of.an gautomobile to indicate the '2 direction and magnitude. of: the flow of. currentthrough theelectrical system.

J ,Ammeters of. .the type referred to must of necessity-be .extremelysimple. in construction in order that their cost-may be kept at a minimum. The ordinary aninieter ofv this type consists of apermanentmagnet, an in- 'dicatingneedle.inounted on a shaft-With a ,magnetio. armature, and a conductor arranged parallel Withthe armature so that .the .resultant lines ofv force aboutlthe conductor Willtend to move thearmature to a position perpendicular to the conductor and ;..against the pull of :the permanentmagnet.

It is-Well knownthat..thedensity otthe magnetie.field. at anypoint adjacentithe con- ,ductor variesinversely :avith. its distance from the conductor, other conditions remaining-the same. A eommon diilicu-lt-y in am- -meters.= of this/type is-11ri equal--deflection,

-lIIllfOIIIbfOl' each unit. change in-the current. ..A marlrn'iay be made on the scale toiindicate thedeflection of theneedle Whenioneuni-t of current flows through the conductor. The swinging of the needle hZLSJlLQVGCl the-armaqture'to a position farther-away from the conductor Wherethemagnetic lines arefewer wfOI a given; unitof current; As'.-the-next unit-of current is. passed through the conductor the intensity of th'e'iield adjacent'the armature has been increased but notdoubled and the deflectionof theneedlefor the. second unit'of current is not so great as thede- :flection for the first unit. -T-his principle -operates progressively as-the current increases and in order to make the scale accuratetthje divisions on {it must be progressively smalleraway tron-1' thecenter orzero point.

"that'is the deflection ofthene'edle is'not.

1927." Serial N0. $053496.

. portional to ithe amount of.current.passing through the conductor ..This. arrangement makes possible aiuni-forrn scale on .the :di al.

Other: objects ot the invention-Will appear in the. course of the following description, taken inconneotion with the accompanying drawing: and appended claims.

. In the drawing:

Figure 1 is a perspective view of the assembled-unit removed from its-case.

Figure 2 is aplan View, With-parts broken .away.

Figure 3 is at bottom viewwith parts broken away.

- Figure 4 is a; sectionion the. line 41-.1-'of Figure 2.

Figure 5-shows-the-for1n ofthe blank from Which the frame is constructed.

Figure 6-; is ail horizontal section through .the .conductornnd armature,- the direction of the magnetiedines of force beingaindicated diagrammatically. by arrows.

Referring toathe" draiving the .numeral 10 .indicatesthe frame, which inthe present case isthe; conductor through JWhich passes I the. current which is to bezmeasured. The conductor frame is formed from asheet of metal'shapedwas indicated. in Figure 5, in .avhich the dotted linesiindicatelines on which the frame is to be given aright angle bend. Ontop of-thc-center section of-the frame 10 is a-permanentbar magnet 12 =held in ,place by-bent up portions 14 and 16 ofthe fra-me. Theportions 16'are bent out-and apertured as illustrated, in order to provide means for riveting or bolting thereto thedial 24. The I framelOis symmetricaland each-side or section thereof is provided with spaccdlegs 17 and 17 and horizon'taLapentured-portions or Wings-18, eachwing-being-bentnp as at 20 for a'p urpose described. below. The/portion 22 of the frame is bent back under the center to provide support for the shaft on wIt is'an'object ofthepresent invention to which the indicating. needle is mounted.

avoid thi s1 ,diificultyby sow-constructing; the conductor and so mounting theiarinature :that. as: the armature rotates it remains iSllbsta'ntia-lly a 1 uniform distance from the :con-

:ClllCtO15 or in'otherwwords, so that the intensity of the magnetic-field-Which acts on the armature will be directly, and accurately -pro- F-roni'anexamination of Fig. 1 it will be --noted that the conductor comp-risesthe wings or feet 18'andthe connecting U-shaped portion-having thelegs 17 :and 17'-and a connecting base portion on whichthe magnet 12 is mounted.-

The-,numeral 24- indicates a strip of. in-

sulating material which is placed between the frame 10 and the bottom of the case 26. The case 26 is ordinarily constructed of a light metal, as aluminum, and is provided with spaced openings corresponding to the apertures in the insulating strip 24' and in the wings 18 of the frame. Fitting within these apertures are the terminals. Referring to Figure 4:, each terminal comprises a bolt 28 provided with a head 80. The head is provided with a straight edge for fitting against the flange 20 of the wing 18 for holding the bolt against rotation. The wing 18 and insulating strip 22L are fixed together by the hollow rivet 3 An insulating washer 36 prevents contact of the nut 38 with the case 26. The construction described provides an insulated terminal for fixing thereto a terminal of the electric circuit.

Referring to Figure 1, the center portion is shown with four vertical legs 17 and 17 spaced as indicated in Figure 6. The bent under portion 22 and the under side of the center of the frame 10 are prick punched to provide for the shaft t0 on which is supported the magnetic armature 42 and needle tt. The needle is provided with an offset portion 45 extending through a slot 46 in the dial so that the arrow shaped end of the needle will be visible to the operator. A glass cover may be fixed to the case over the dial in the usual manner. One section of the conductor is divided into two legs 17 and the other section into two other legs 17. The plane of the armature shaft 40 is parallel with the legs 17 and 17 in any position of the armature the latter being normally held by the permanent magnet in the position illustrated in Figure 6. WVith the armature and the legs of the conductor arranged as illustrated, the direction of the magnetic field is. as shown in Figure 6, it being obvious that the current goes up the side 17 and down the side 17' or vice versa. Thus the field about the conductor tends to turn the armature from the position illustrated to a position at right angles thereto. The four legs 17 and 17' are so spaced that the lines adjacent the armature are in a curve which is in a general way concentric with the shaft 40 supporting the armature. As current passes through the conductor and the armature is deflected, .it moves in asubstantially uniform field and gives a quite uniform deflection for a unit change in current.

I claim:

1. An amm'eter comprising a pivotally supported armature, a conductor provided with terminals for connection in an electric circuit, said conductor comprising portions extending along and adjacent to the axis on which the armature is supported, each portion being divided to cause the lines of force resulting from the passage of a current therethrough to extend arcuately about said axis, and a permanent magnet tending to hold said armature against rotation.

2. An ammeter comprising a pivotally supported armature, a conductor provided with terminals for connection in an electric circuit, said conductor comprising side portions extending along and adjacent to the axis on which the armature rotates and on opposite sides thereof, each side portion being divided to cause the lines of force resulting from the passage of a current therethrough toextend arcuately about said axis, and a permanent magnet tending to hold said armature against rotation.

3. In an ammeter, a conductor comprising two substantially parallel portions offset from each other and connected at one end, each portion being divided into a plurality of legs, an armature mounted to rotate-on an axis between and substantially parallel with said portions, and a permanent magnet tending to hold said armature against rotation. V

4. An ammeter comprising a pivotally supported armature, a conductor having side portions connected at one end and extending along and adjacent to the axis on which the armature moves and on opposite sides thereof, each side portion being divided into legs substantially equidistant from said axis, and a permanent magnet tending to hold said armature against rotation.

5. In an ammeter, a conductor frame comprising a central portion and side portions extending in offset planes, each side portion being divided to provide an extended held of force thereabout on the passage of an electric current through said conductor, an armature pivotally supported on the central portion of said conductor frame between said side portions, and a permanent magnet tending to hold said armature against rotation.

6. In an ammeter, an armature shaft and an armature supported thereon, said armature extending in a plane disposed axially of said shaft, apermanent magnet tending to hold said armature against rotation, and a conductor comprising side portions along the outer edges of said armature, each side portion comprising a plurality of legs.

7. In an ammeter, a conductor comprising wing portions and a U-shaped portion, each side of the U formed into a plurality of legs, and an armature and pointer swinging mechanism mounted within the U and between said plurality of legs whereby a substantially uniform held about saidarmature is obtained.

8. The structure of claim 7 and a permanent magnet mounted on the base of the U and rigidly held thereon by integral portions bent from said conductor.

9. In an ammeter, an integral conductor having lateral wing portions and a U shaped central portion connecting the Wings, a magnet, integral tongues bent away from the full length of each side or leg of the U and adapted to assist in supporting said magnet on said conductor, and an integral tongue at one side of the base of the U bent under the base and with the base adapted to support a pointer and armature.

10. The structure of claim 9, and integral tongues extending from the base of the U over the magnet to rigidly hold it in place.

11. The structure of claim 9, and a dial mounted on the tongues bent from the legs of the U.

In testimony whereof I aflix my signature.

RALPH OLAF HELGEBY. 

